Original subtitles

hello everyone and welcome to this

iskarsa webinar on earthquakes and

traditional construction

my name is timmy heals and i am a

structural engineer at old structures

engineering in new york and adjunct

professor of historic preservation at

columbia university

today's webinar is brought to you by

ikomos iscarsa

or the international scientific

committee of the on the analysis

and restoration of structures of

architectural heritage

as several of you might not be familiar

with iskarsa i will briefly introduce

our scientific committee

before we get started with the webinar

we are an international group of

engineers architects scientists and

educators dedicated to the restoration

and care of build heritage

we mostly focus on the structural and

technical aspects of conservation and

architectural heritage

we have an elected board

many of whom are here with us today our

president

goron arun will be our first speaker our

secretary general tom morrison

is always working hard behind the scenes

um

letting people into the meeting room

monitoring the chat and so on um

the goals of viscarsa are amongst others

to disseminate knowledge

promote international cooperation and

organize international training programs

another goal is to collaborate with

other scientific committees so we are

very glad today that we have

speakers who are also active in iska the

international scientific committee that

works on urban heritage from icomos

and icorp which works on risk

preparedness for this webinar

in the past years iskarsa has published

principles for the analysis conservation

and structural restoration of

architectural heritage we publish

newsletters as well

currently we are developing um

guidelines for the

analysis and restoration of structures

of architectural heritage

and before the pandemic we were

organizing yearly workshops

the latest ones were in korea like this

one uh

turkey here's some pictures of um

that workshop um and then the very last

one was in october 2018 and was held

in iran we look forward to continue this

once the pandemic is over um

you can reach us on at the following

email that is coming up when my slides

pick up there we go

um is iskarsa gmail.com you can follow

us on facebook as well or you can find

us

on our website

okay that brings us to our webinar on

traditional construction

and earthquakes we wanted to highlight

traditional

structures made from for example wood

masonry

or earth in seismic areas because these

buildings are often seen as the most

vulnerable to earthquakes yet often

these buildings have seismic mitigation

threat

strategies built in as part of their

original construction or past repair

all too often unfortunately this

built-in knowledge

has been lost or is misunderstood

as the safe keepers of all buildings in

earthquake areas

we all grapple with similar questions

how do we balance on the one hand

the life safety of all the users of a

building and our desire to preserve that

building for future generations

and on the other hand how do we

implement a minimum intervention

that is the least intrusive to that same

building

sometimes engineering solutions take a

conservative approach

that try to maximize structural strength

yet they go well beyond what is actually

needed to ensure life safety

often this damages valuable elements of

the building

and those well-meaning interventions

might paradoxically in the end

contribute to a building's destruction

additionally

the regulatory framework provided by

building codes to deal with traditional

buildings is often lacking

therefore we need to study learn and

discuss

traditional architecture building

technology in seismic regions has

evolved over centuries and has developed

what is referred to as

a local seismic culture today we have

five distinguished speakers from five

distinct regions around the world who

will discuss their local seismic culture

we also hope to hear from you we look

forward to taking your questions after

presentations feel free feel free to

post them in the zoom chat window at any

time

we would also like you to consider

presenting on your own work

on traditional construction in a

follow-up webinar probably held

at the end of march a call for

presentations will be distributed

shortly

before handing over the floor to our

speakers i would like to thank

evan speer and tom morrison who are my

co-hosts today and who are managing the

webinar logistics

behind the scenes i would also like to

thank the mem other members of the

organizing webinar committee

steve kelly kaiweisser goron arun

krieger angeli you

chola aquintunde stacy wallis and maya

segarra lagunas

finally i would like to thank all of our

distinguished speakers for agreeing

to share with us their work

so then without further ado i would like

to introduce you to our first speaker

professor goron arun who is also our

president of

ikomos escarsa she is full professor and

dean of the faculty of fine arts and

architecture at hasan ka leonchu

university in gaziantep turkey her

research focuses on diagnosing the

structural problems of existing

structures

including buildings made of masonry

timber early concrete and steel

located in seismic areas she has led 12

national and international research

projects on historical structures

authored five books and written more

than 200 scientific papers and reports

on heritage

welcome madam president you have the

floor

thank you

okay shall i share my screen yes please

okay good morning good afternoon and

good evening

for all of you i'd like to thank thank

all of you

participating from different countries

for being here with us

this pandemic period kept us from

meeting face to face

and to share our experience and enjoy

spending time together

but the constraints of this

period also enforce us to use digital

communication

i hope this webinar will serve to

increase

synergy among us now i will present

my topic is traditional earthquake

mitigation measures in anatolia

this presentation is consisted of

construction methods

of master builders from various

civilizations lived in anatolia

it is based on experience made during

diagnosis phase of

restoration works and reviewing

archaeological and history of

our arctic publication

for those who don't know the place

anatolia is far west peninsula of asia

okay earthquake was

and still is one of the most threatening

actions

to build buildings in anatolia as you

see here

vernacular or monumental most of the

heritage structures

are earthquake area

in anatolia main construction technology

till mid 20th century was timber amazing

about you see the different types of the

timber structures and below you see

different types of mason

structures

in most places due to the scarcity of

wood masonry structures were built

and most of heritage historical heritage

survived up today are amazing

transaction

is amazing the master builders of the

past

designed their when designing their

building they were responsible for every

aspect

they had to assume the roles of

architect civilian

structural engineer mechanical engineer

as well as the city planner and the

contractor

today we say a earthquake

resistant design is necessary in order

to make the building safe and in

earthquake distance design it is

suggested to

maximize the energy absorption capacity

of the structure

and minimize seismic action

to maximize energy absorption capacity

of the structure

energy dissipation has to be provided

the dominancy has to be provided

and geometrical irregularities has to be

avoided

to minimize seismic action building has

to be light

weakening effects on the building has to

be avoided

and amplification of ground acceleration

has to be minimized

building masters use

developed from previous cultures their

own trial and error

and techniques are transferred from one

generation to another

they were able to size and design

their buildings taking proper account of

the environmental

conditions

let's see how these demands are met by

our master builders

to dissipate energy the masonry

structures with sand lateral loads

this compresses strength of its material

friction between the units

the movement of the units

the movement of the units is important

to disperse energy

in connecting stone units with each

other

they placed metal connectors in lead

which

is very soft material so that it lets

the units

move under lateral loads to disperse

energy

if they are using a mortar to connect

the units

then they used weak rather than strong

so that it can slide the units can slide

on the lateral loads on the during the

bed joints

and dissipate energy

the repair of the motor is

is not so hard but it keeps the

main structural units

redundancy has to be provided redundancy

of the structure depends on the nature

of the structural system

and detailing of its elements but

masonry structures are inherently

redundant structures

building masters knew the physical

dimensions of height to sickness ratio

and length of thickness ratio of the

wall are

important factors in seismic performance

of

nasals

they provided horizontal lacings that

tied the outer faces of the walls

this prints rolled bulging under gravity

loads

and reduces the slenderness ratio of the

wall

these lacings could be brick and stone

or metal in stone walls timber in greek

stone or other levels

a provided vertical words

at certain in intervals to the long

rules

this could be a cross walls and

intersecting

or vertical ties or of timber or stone

mattresses

to avoid geometrical irregularities as

long projecting and different weighing

components of a building buildings were

separated as specific joints here the

building parts staying side by side

were separated by not joining the maze

limits to each other

the foundations were also separated

to minimize the

earthquake effect

building has to be light but main

reasoning is

heavy the construction

the only way to reduce the weight of the

structure was to make

light roof and floors in places where

there's no wood

masonry walls and domes were built to

span the plan areas

the building masters knowing the

geometry and behavior of the walls and

doors

they used clay pipes in the area of

compression

to reduce the weight

to construct the flat roof over these

nose or balls

uh between the flat roof

or floor and the

walls they empty the space in between or

use clay pipes or amphora

to reduce the weight of the

building

again to make the building lighter in

multi-story buildings

in seismic areas we constructed getting

gradually lighter

and upper floors with walls with

material

and the thickness of the wall this

for example when we look at this the

three floor

building ground floor is masonry second

floor is timber with

brick infield the first floor sorry

second floor

is bad id that means the frame timber

frame

left empty inside

uh in the middle the ground floor is

amazingly

first floor the the

but the inner walls are timber second

floor

is totally timber timber

here is the ground floor is masonry the

first floor

is mainly but inner walls are timber

this way the building gets lighter at

upper floors

and the center of gravity of the entire

structure

is brought closer to grade to meet the

seismic demands

to avoid weakening effects of course

water

is a nonsense mix threat to all kinds of

buildings

timber organizing depending on the

porosity of the foundation construction

material and soil characteristics

it can damage the wall and soil eroding

away

portions and by reducing the strength

and moisture in building causes loss of

material

and weaken the structure in long term so

water drainage was given high priority

during its design and construction

to prevent insulin instability of the

building from undergo

underground water woman seasonally or

daily and to collect the surface water

of rainfall they designed an effective

drainage system the major components of

this drainage system

was wells orchestra in the basement of

the building

a galleries or channels

to discharge the water out of the

building

and gates for ventilation

because this application is forgotten

when a new construction has to be built

beside an old masonry or timber

construction

they it breaks the discharging system

then the water starts to raise to the

building

weakening the material and softening the

soil so that

leads to the foundation settlement of

the building

to minimize amplification of grand

ground acceleration

of course it has to do with the design

of the foundation

usually the soft soil was consolidated

by timber piles

the timber piles were tied by a timber

mesh

embedded in for some water the

foundation walls rested on this platform

the foundations are amazingly your

timber building was amazingly

the sick foundations were generally a

vertical role in the soil

as the both sicknesses became sinners

the foundation

was widened at the foot if the wall was

composed of closest paced

piers then and there is no sufficient

depth to step

the foundation and inverted arch or

walls

were made

master builders knew that the

acceleration

generated by ground displacement is

amplified

or

created by soy structures in high

systemic zones

the building masters interview

introduced special techniques

in foundation construction to provide

natural stability

if the rock back or hard soil was deep

the foundation was

rested on a slow layer of sand gravel

or small stones in a

amazing village houses in anatolia

were constructed over a layer of

approximately 40 centimeter

sand till 1960s that's

where when the rainforest concrete

became popular

in villages also

if the rock bed was close to the surface

a flexible base was provided by

placing single or more layers of wood

foundation

at the foundation base in the

foundation most of

the buildings is

guitar you see i uh rest

here in the project of inverted world

foundation of edenica

system from 19th century

[Music]

you can see the timber grillage at the

bottom

so this foundation is resting on

the two layers of timber village

if the rock bed was standard

the rope was carved in the form of

trough

so that each stone on the foundation

wall could be placed in the rock

as if resting in a cradle

here the big dress stones of the wall

rested on high edges of the turf not

inside

the space in between was filled with

briar pieces of coal or animal skin

to reduce the friction at the bottom you

see malabari bridge

on southeast of turkey

the

a different foundation

system practice was found

during that automaton

around this octopus six meter high

two meter thick wall at a four meter

distance to the uh to the tomb was found

and it was the shape of the octagon

this is as if the octagonal and

hexagonal forms are not adequate forms

for earthquake

areas so this buried wall

acted as a retaining wall to absorb the

first shock of earthquake forces

and there is no damage in this octopus

another

this obelisk experienced many severe

earthquakes in its lifetime

but had no damage when you look at it

closely

the obelisk is placed three centimeters

inside

and this is on a cubic marble

three meter each side and this

cubic marble rests on another marble

uh platform uh four to four to three

meter high

and at the corners there are granite is

cubic granite stones with rounded edges

could these grannies be seismic

isolators of this antenna

okay

okay to confirm previous cultures

their trial and error and

transfer our knowledge from generation

to generation

were able to size and design their

structures

they connected mesa units properly so

that they dispersed energy

provided seismic joints but not by not

connecting the different weighing

components of a building

they had knowledge on geometry and

behavioral structural

elements they used lighter construction

material on upper floors to hold the

center of gravity of the building close

to gray

we designed an effective underground and

surface water drainage system

in earthquake areas change natural

frequency of soil

or provided flexible base flexible base

okay thank you this is my presentation

and i'll

give you some reference which i used

to interpret what i have seen what i

have met

during the diagnosis phases

to understand why these were

constructed that way this this

references really helped me a lot you

see

the this the oldest one is from

1570 and the young ones are

the archaeological

excavations thank you

thank you so much for that wonderful

presentation professor arun

um we will move on um i will also just

repeat

uh for the people who just joined

welcome uh you can ask

questions in the chat if you have

questions for professor arun you can

post them in the chat now we will come

back to them later after all of the

presentations

um right now we will move on to the next

presentation which is by

kai waisa from nepal kai waisa is a

nepali of swiss origin who studied

architecture in zurich

he is presently president of ikemos

nepal and has been involved with

management of world heritage properties

in asia for the past two decades

since 2015 earthquake since the 2015

earthquake in nepal and the 2016

earthquake in myanmar

kai has been involved in post-disaster

rehabilitation including the restoration

and reconstruction of

historical monuments welcome kai

good evening from kathmandu

let me share

uh so good evening uh

in cap from kathmandu my uh

presentation is on uh rebuilding custom

end up the challenge of using

traditional technology

um on the image one sees the actual

protagonists

of uh this project we have the

member of parliament uh rajya sakhya who

is

actually sort of the responsible

to deal with the political aspects and

then we have the two

main artisans on the left we have

the main carpenter

and to the right our head mason

and here you see uh they're carrying out

one of the the many rituals that is part

of this

reconstruction process um

just a very short introduction of course

to the

to to the earthquakes that take place

along the himalayas and the ones that

have affected

the kathmandu valley uh the most recent

one was of course the 2015 gorka

earthquake which was

7.8 magnitude and previously we had the

1934

nepal bihar earthquake of 8.4 magnitude

so we see that sort of every 80 to 100

years we have

a large earthquake impacting the kappa

new valley

um the case study is this

uh astomandap which you see an image

on the left which did not collapse

during the 8.4 magnitude 1934 great br

nepal

earthquake uh there were major

restorations that took place in 1966

followed by repairs in 1972 and 84

and probably in between several other

sort of repairs and work were carried

out

to this monument and but the custom end

up collapsed during

the the the recent 2015 gorka earthquake

of magnitude 7.8 so

the question is you know why did it

collapse during this earthquake

and why did it actually survive the

previous earthquake

and this was sort of been one of the big

questions that keep

arising and we're still struggling to to

actually understand

uh you know try to dealing try to deal

with this question

the sad situation was that when it

collapsed there was

a blood donation going on and quite a

lot of people

died so it was a very traumatic

experience um the customendap

is a pavilion a timber pavilion but we

also have a bit of

brickwork around the core uh

which sort of complicates the entire

structure

uh trying to understand its structural

[Music]

sort of character

and the importance of the structure is

that it gave kathmandu its name so

mandu is the timber

structure or monument or pavilion and so

kathmandu was named after this monument

so

it of course has a major significance

uh and once it collapsed it became quite

uh

sort of a a politicized issue

now the initial uh sort of structural

assessment that was done

and the original design that was

prepared

came up with a whole series of

recommendations which are some very

standard recommendations that are made

for all our monuments in the happening

valley the

the roofs have a thick layer of mud

which

the tiles are stuck into so the question

was that it was too heavy and

we needed to reduce the load on the roof

another point is that there wasn't

sufficient stiffness and

the traditional monuments don't have any

diagonal bracing

and the floor not even on the floor so

the question was how

you know how to introduce uh this uh

diagonal bracing to

provide a certain stiffness to the

building

the timber joints are inadequate so the

question was how do we strengthen these

joints using various uh

you know like metal brackets and

additional

interventions then the question of

the brickword not being reinforced

so in this monument we actually really

have brick and mud mortar

with no sort of reinforcement

so the question was how to introduce

sort of horizontal vertical

ties then we had sort of the mud mortar

not being strong

so we needed a stronger mortar or the

use of additives

uh the question also rose of having some

kind of a

plinth level thai beam which uh

the the suggestion was

to use concrete and the question of the

the

foundations not being sufficient and

that we needed to have some kind of

micropiling done

however all these suggestions were not

accepted so

this sort of activist led community

protests

uh wanted the monument to be rebuilt

as it was the question of course arises

what that means

but the point was that they did not

want these sort of uh

foreign interventions introduced to this

monument

and this actually led to the

reconstruction

being halted for three years and

and you know only in 2018 could we

actually begin the reconstruction

of course taking into account that we

needed to rebuild it as it was

now that was of course brought up a lot

of uh

questions during these three years

uh we were actually able to do a lot of

research which was again

good in a certain sense uh there was

uh archaeologists actually from durham

university

excavated into the foundations and we

found

that the foundations were the brick and

mortar were in perfect condition uh

however

a lot of the timber joints and the the

timber had

deteriorated and especially the link

between the main timber posts and here

in this uh uh image one sees the

keystones where the main

four posts were uh supported by

by the keystone and one of the four

uh stones was actually missing so

probably somewhere in between

uh the deteriorated timber was just sort

of cut at the bottom

and and the flooring was sort of shoved

underneath

one of the four main central posts which

means that

structure was actually standing on three

of its main

uh central posts and sort of these are

the kind of

uh things we we found that it was

actually

these kind of interventions that would

have been

probably one of the main causes for the

collapse of the structure

uh we also found uh through dating that

the brick foundations were

the oldest part from the seventh century

which was actually three four year year

100 years

older than what we thought it was we had

the main timber structure from the 11th

century

and we even found the sort of an old

the oldest timber bracket which was from

the fifth century

that had been reused in in the structure

um so starting with the reconstruction

again the task was to rebuild it as it

was

using traditional technology materials

know-how and of course this also was

linked to

traditional sort of rituals and here on

the left one sees

the the vajrayana priest carrying out a

ritual

and also including blessing of uh

of the artisan's tools

with the starting with the foundation

the brickwork we found

that the brick bricks were very

specifically

uh there was a specific scale to the

bricks the size but also that

foundations had smaller foundations

where eight courses in three

levels and the deeper foundations were

12 courses each

in three levels which meant that you

know all

the proportions had to also be

considered when we

started reconstruction which meant

ordering

bricks off the spec specif specific size

that we required

here we see the the our head mason

uh working on trying to get the right

uh mud mortar consistency

so we actually had to sort of uh develop

uh you know the understanding of of the

the brickwork and the the mortar to use

in this

monument now already in the beginning

when we

removed the rubble we saw that the

the plinth was actually uh sort of wavy

which meant there must have been some

kind of settlement but

looking at it more specifically we

realized that of course there wasn't

any settlement foundations were in

perfect condition

but actually there was uplift in the

areas where we did not have a structure

sitting on top so wherever we had a wall

or our

post it actually confined the masonry

while the areas in between there was

uplift

so this is actually quite a different

sort of a

response or effect on on

the the brickwork uh

which is again we had to remove about

four or five courses

uh and relay uh the the plinth so that

we could

bring it to a a proper level

uh the other big issue was of course

getting the artisans

uh who could work with the timber which

was of course the main

part of this structure and luckily we

have the the artisans

and to some degree we could reuse the

the timber elements but

a lot of it we had to replace or use the

old timber and reuse

it but luckily again with

with the knowledge of the artisans it

was possible to carry out this work

on the right we see the bamboo

scaffolding now

it of course looks very uh traditional

and it looked very good but

it was actually also very practical

because it was much more flexible than

the you

using uh pipe trusses and

it was uh to to pull up the the

timber elements it was possible to do it

by hand uh meaning using ropes and

human power and not use

any uh heavy machinery which then also

allowed the sort of communities to

participate in the process and help

carry these

uh these timber elements uh to the

site now with the timber

uh again we have a you know over i i was

told over 150 different

uh joints we still need to do further

research on this

so supposedly a lot of these uh

traditional joints have

already been forgotten we're trying to

we're hoping to actually get the

the artisans that are still around uh to

help us document these uh

these uh joints uh the main

characteristics is of course that it's

fully timber joint uh where we have uh

sort of pegs holding the for the

different pieces

together and uh this has been of course

part of

this uh adaptation to uh the seismic uh

requirements of the structure where

certain movement

is is allowed and

and it sort of holds the the structure

together

uh the problem we actually faced was

was with the brickwork where in the

foundations we of course

found the uh the

brickwork in in perfect condition but uh

in the superstructure there was a a lot

of damage which was there uh

possibly even before the earthquake but

then of course after the collapse a

large part of the

there was additional damage to do this

uh to the brickwork

and uh there was a lot of discussions on

how to deal with this and

of course the question was of how

to ensure that the brick

components of the monument were better

reinforced

this is a big discussion and i've

discussed this with

many people including arun menon

and also randolph i spent many hours

discussing with him

hopefully he's also listening in on this

because i've used his images

the traditional monuments in kathmandu

actually have horizontal timber lacing

but very often they don't use

uh vertical elements so it's actually

really

just a horizontal timber lacing holding

the the structure together

uh on the other hand uh which is again

sort of similar to uh to the

construction

in kashmir the the construction

we have of course the other uh

possibility

of timber framing which is found in many

parts of the world

and also the example in in kashmir

but this is not used very often in

kathmandu we have found it in a few

places where either

the the the structure like for example

in the nine story

uh palace where the the structure has

been

much larger than traditionally uh built

where sort of vertical elements have

been introduced into the brickwork but

this is actually not commonly used

what we actually saw also in bagan

was the the whole question of

confinement of brick masonry

and here sort of steel caging around the

brickwork

uh was very uh effective

again the question here is how do we uh

ensure sort of this confinement or

reinforcement of

of brick masonry in in mud mortar

uh that's again uh i've raised a lot of

questions and

we haven't really come to detailed

conclusions on this i think it still

requires a lot of research

what we ended up doing in the custom end

up was

sort of introducing a very minimum

timber uh sort of reinforcement

into the brickwork uh sort of uh

to to ensure that there is some form

of confinement but

keeping it to a minimum that it doesn't

really take over

uh the function of of sort of a you know

sort of

timber framing with the infill and

this was really to ensure that the

the brickwork does is able to take on a

certain level

of stress

the the this is the present status of

uh the custom end up we're uh just about

uh

completing uh completed the the main

structure

we're still waiting for timber to be uh

provided for uh the remaining roof

structure

what we're working on is also a

continuity plan since we know

we know that one of the main causes for

the collapse was

the lack of maintenance

and uh sort of the the requirement of

managing the structure over time

we are working on uh a continuity plan

which includes uh sort of the the

maintenance and monitoring of the

structure we're hoping to put in

sensors as well and do structural

monitoring

but also that we manage the the use

of the monument and the continuity also

includes uh here on the lower

uh image we see one of the brackets and

this is actually from the

the fifth century so uh there's a

continuity also

in respect to material

as a conclusion uh it's always this

question of how do we

deal with sort of the traditional

technology materials and

here uh sort of bringing the the

scientists here is uh professor ian

simpson from

sterling university taking a sample of

the timber while our

uh head carpenter watches he

looks very skeptical but on the right

side we've

managed to get him to try out the

resistometer

traditionally of course you just knock

on the wood and you know how

you know whether it's good or not just

by listening to it

but again the the question is how do we

bring this traditional knowledge and

modern

technology uh to to actually

communicate with each other to be able

to deal with these monuments

we're actually planning our inauguration

this on the 25th of april this year

it would be the six years after the

earthquake and three years after we

started construction

but we're not quite sure whether we'll

manage to complete it by then

we're still hoping to do so uh

thank you very much

thank you so much for that wonderful

presentation from nepal kai

just a reminder to everyone keep the

questions going in the chat we've gotten

a great set already and we will discuss

them

after the five presentation we will now

move on to our

third presentation which will be by

grieger angeliu

he is an assistant professor of

structural mechanics at the department

of civil and environmental engineering

at the polytechnic of

milano his research focuses on the

application of modern technologies for

an improved diagnosis of the structural

safety of historic buildings related to

earthquakes

aging or soil settlements this includes

a combined application of fine of the

finite element method parametric

modeling

lidar scanning and structural health

monitoring welcome grigor the floor is

yours

thank you tim

you can

um sorry can you see can you see my

screen

yes you can okay thank you so

thank you everybody for attending this

this seminar

i will be talking today about the

earthquake in of

november the 26th in albania

so i will be

talking about the post-disaster damage

assessment of historical buildings

about the content of the presentation i

will

discuss a bit on the typologies of

historical building

in uh in the earthquake region

just go very briefly on the shape map of

the november 26 event

i will present some damage survey

statistics

on the earthquake area and then

i would prefer here to discuss three

case studies

which in my opinion are the most

significant ones

and then i think that is very

interesting also for the audience here

to go um let's say through a detailed

structure assessment in one of the case

studies

the tower c in the castle of doors in

albania

and then i would like to draw of course

some conclusions with

uh regards to the earthquake

historic buildings and uh the strategy

for

for the reinforcements and the rebuilds

so because of let's say the big audience

here

from all the world albania is located

in the belkan region just beside

italy and greece so

this uh territory characterized by uh

moderate uh seismic events

um here i'm just plotting um

a map you know from the u.s geological

survey and you can see

here um some of the events with a

magnitude of

5.5 now since january 2019

so i mean there are continuously

let's say important um important

earthquakes the majority of

the earthquakes that we have in the

country is uh characterized by

low to moderate intensities usually

less than seven winter

and rarely with high intensities event

with a magnitude more than seven

um it is important also to

see what are let's say the the types of

buildings that we have

in in the region of the earthquake

now there are different types of

buildings

we have cult buildings related to

to muslim or to christian religion

here you can see for example uh the

tequila of dolma which was damaged

during the earthquakes

we have a vernacular architecture from

the 18th or 19th century

this is an example this is the

ethnographic museum of korea

we have um engineering for

infrastructure as

bridges aqueducts here for example

is the where tobacco one of the bridges

in

in tirana but we have also castles

as this is the castle of malaysia for

example

there are many fortifications in the

area but we have also um

what we call design buildings so

these are mostly of the 20th century for

example

this is a building of the 20s

and 30s um

here you can see some uh of a number of

buildings

i would like to to state here that uh

when i'm talking about historic

buildings i am mostly focused here on

designated historic buildings

so it means that we could have more

historic buildings but these are the

designated

historic buildings according to the

albanian law on

cultural heritage and you can see here

uh some of the numbers

um now

with regards to the earthquake most of

the buildings

so the majority of them were located of

course in the region of duras

the the region of tirana and the region

of legion

of course there are also examples of

damages in the other regions as albasana

but that is not the majority of the

cases

so with regards to uh the earthquake

which was very very devastating of uh

november 26 2019 uh here you can see

um the the stigma where

um you can see that the the earthquake

was

uh pretty pretty severe you know in in

the region close to

duras and then uh quite strong you know

in the other region so for example

close to the capital in iran where we

have a very high density of

buildings in korea or also

in the asia which is located here so in

this reason we have

very devastating effects of course here

i would

stop in the case of discard the case of

history

now there was also a very

interesting thing which has to be

discussed in my opinion that before the

earthquake of november 26

we had al also another earthquake in

september

21st um so just two months before that

you know with a magnitude

lower in terms of magnitude but still

with

provoked damage in in the buildings of

course

not so heavy as the last one but i mean

the world damage and

uh probably you know just the two months

period

did not allow for a proper survey

and proper repair of this damage in many

buildings

not only just the historic one so

this is a very interesting point which

has to be on the line here

um here you can note um the three

regions you know

of the earthquake this is the epicenter

uh and these are some data uh

collected by the national institute of

cultural heritage on a stock of

110 designated building so on a stock of

110 designated building

10 percent was like previously damaged

and then we had more or less 40 percent

with negligible damage

25 26 percent with moderate damage

and more or less

25 22 23 with very

severe damage um so this is on

um on the stock of um

110 billion um

it is very interesting to see because i

mean from from that point then

we can also generalize about the damage

that the earthquake caused in

buildings in the country

um so these were some general statistics

about

the earthquake um i think it's uh

it's good for us now to focus on uh on

some of

the cases um now i have chosen

three cases belonging to the same

let's say structure topology towers

because i think that these are the three

most significant

ones but are also kind of communicative

so also easily to understand but also to

make comparison between uh between them

so i will be discussing the the power of

kruya

located here the tower of preza

and the tower sea indoors of the

duran's fortification um so

we start from the one let's say it's a

bit more far from the epicenter and more

or less we go

we go closer

of course each of each of these examples

has let's say

its own characteristic and specifics

this is the tower of brezza you can see

on the left

an image of the tower before before the

damage

this is an image of 2013

and you can see on the right and an

image

after after the damage of 2019

um so the complete upper part of

the tower had collapsed

um it is very important in this

in this example to see the presence of

pre-existing cracks

so you can see clearly here i i did not

try to highlight anything

because in my opinion is pretty evident

that you can see you know the presence

of um

of the cracks you know already in 2013

and the same one of course after the

earthquake

got magnified

you know but

[Music]

it looks like you know the world let's

say an important factor in

in the part of the collapse something

very interesting here was an uh an

addition you know

recently but more or less like two years

before the collapse

and you can see that the lower part of

the construction which had the insertion

of

some steel ties resisted pretty well

what is more important here is the

the other part of the tower so you can

see again another image

from before and after

and again in this in this area here

you can see already you know the

presence of of the cracks

so again um it is

um shown here how the importance of the

presence of these pre-existing cracks

it is very important in the structure

behavior of

the earthquake so i would like to

highlight

here the importance of the survey you

know

already on site

now i would like to pass to the second

case study

this is the tower of kuya of course this

is a much bigger tower

compared to the previous one

but again beside the specifics of each

case

i would like to draw here a comparison

between the first and this one

in the sense that you know the part of

the colonnade in the upper part in this

case did not collapse

now if you make a comparison between

this one

and this other one and um

the reason it was because you know this

one here was basically rebuilt in

concrete

um during the 70s or the 80s

more or less uh and in the

in the zoomed part of this you can see

here

uh the reinforced concrete beam

on the base of it which basically during

the earthquake

more or less floated you know in this uh

soft layer of mortar so it's some kind

of

base isolation at the end

but uh another important aspect here

is you know to make a comparison between

this facade

and this other one here

so uh this part of the facade

and this other one

the the importance is in the fact that

in this part of the facade you know the

damage was

more or less pretty limited

but on this one you see that

you know the damages is pretty important

um so if we analyze them

more in detail um the part of

the technology of construction you can

see clearly here

that we have timber ties more or less

placed regularly you know one

every a meter or a meter and a half

so these are the two edges of the tower

basically

and it is demonstrated here quite easily

that uh this traditional technology of

timber ties

you know it's uh it's it's a good one

you know in helping to prevent

seismic damage of course there is some

damage but it's

much more limited compared to uh the

other facade

so this is an example of how you know

when

the existing

seismic anti-seizing system exists in

the building you know it

works

this is another example of

another tower this is in the city of

duras um so also here we have a local

collapse so a big portion

of one of the towers this is the tower c

uh collapsed

what is very interesting in this case is

that we have

also um you know

two other towers with the same geometry

just let's say like

uh 20 meters you know uh from this side

and 20 meters from the other side and

the two of them did not collapse but

just this one has these

local collapse i would now

show um in detail you know some of

um the structure assessment procedure

then we performed in this case in order

to

analyze this case study i think that

that would be also

interesting for for the audience

this part is divided mainly in in two in

two parts

one is the data collection and analysis

and then the

the structure analysis procedure

the idea behind all of this is to have

let's say

certain proof certain scientific proof

on the causes of the collapse

and this of course will help in the

the restoration

so you can see on my

on the left side of the screen for the

grammatic

survey of the tower the tower was

built in uh by the amp the byzantine

emperor anastasia the first in the late

century

then it had um

you know during the earthquake of 2073

there was

collapses you know in the whole city

walls

and part of the tower was was damaged or

collapsed

this one as you can see here and then

there was let's say a major

reconstruction process of the city walls

um and after that

we have another late phase during the

ottoman

empire which is this one signed here

according this research is according to

professor jarakarisky who

is a noted scholar for the analysis of

the fortification

in november

this is the geometry of the tower and

during the structured survey

we noted let's say some weaknesses in

the tower

the first one you know first of all this

is the block which collapsed

this is a huge one actually and we noted

um let's say uh the first

weak plane which is this one here was a

second one

uh this one here which is also as you

can see is pretty much flat

and is uh connected also with one of the

phases of construction

but another very interesting

discovery was this cavity this void at

the base of more or less at the base of

this activated block so we had to be

certain which was

the main cause of this collapse

finally we performed also analysis on

materials

and in conclusion i mean the mechanical

properties here were

were pretty good um

another part is um which we discussed

was the part of

the seismication these are some

accelerograms which we

recorded in in the city of doors this

was recorded from the doors

station but unfortunately we have just

15 seconds of the registration

so all the calculations there will uh

are performed just with

uh with these numbers finally

um with regards to uh

to the spectral uh to the spectral

acceleration

it was very interesting in this case to

make a comparison between

the the earthquake spectrum and the one

suggested by the design code

and it was noted that it was more or

less you know

more or less you know the spectral um

the spectrum of the earthquake more or

less what was suggested by the design

code

so it confirmed let's say on on the

strongest of

the earthquake here you can see

if you would like to go into more detail

also a comparison between the one in

blue

and the one in black between the

earthquake of

november 26 and the one of

september 21st so you know we had

two quite strong earthquakes although

you know the first one

was not felt that much you know did not

have that much damage you know

compared to the second um

here we can see a finite element a model

of the tower you know in order to study

much more in details and

for sure on the causes of the collapse

this is the model analysis it was

interesting

without stopping here in much detail to

observe you know here some similar

similarity between the collapse

and some of the modes in in the

numerical model

we analyzed the effect of the soil

settlements

and what came out was that you know the

major

one of the major cracks this one here or

the

one of the let's say important weak

planes that we we saw there

could have been related uh very strongly

to

settlements so

in some kind of way this somehow

excluded you know

the first weak plane as as one of the

causes of the collapse

um in order to have also some um

you know some more simple

analysis you know were performed here by

also

limit analysis

um

the result of of this analysis showed

that

um you know these were the the kinematic

multipliers

and the results showed here that

the failure you know in this direction

would have been

let's say the first one uh so

it kind of let's say highlighted that

you know the the surface here which was

very flat and

with did not provide any friction you

know

would have been one of the major causes

of the collapse

while you know the weak plane one here

could not have been let's say the major

one for the collapse because of

um you know if we calculate here the

multiplier you know with the friction

you know

the safety would have been pretty high

um in order to give to this you know the

final

um final assurance you know on the

collapse

we performed some time history time

history analysis

um with uh the actual accelerogram

and you can see here that at the

simulation time of

more or less 12 seconds um

you can see the formulation of damage at

the beginning

in in this in this area you know close

to

the construction joint where we have a

very flat

uh surface you know in the masonry

so no friction you know to guarantee the

continuity of the structure

and then after some time we see also

you know some development of the damage

close to where we have actually

uh the cavity in the model so

at the end you know this kind of

confirmed that you know the damage

arises

firstly at the point where we have

[Music]

this construction joined and then you

know developed

through develops through

the part of the cavity confirming these

two points you know as

the most important factors you know to

cause actually a collapse

so this is one last

simulation to show you know how

the the collapse happened

and you can make here a comparison be

with um you know with

the actual mechanism

this is also important in order to

understand you know the kinematics of

the collapse for later reconstruction

so uh with this i conclude the the case

study number three

and let me draw here conclude here with

um

with these conclusions uh regarding

the seismic events in albania first of

all it is important to say that we had

two seismic events

within a short time frame which did not

allow for

time for a proper survey and repair the

business

regarding the

[Music]

the restoration strategy the and the

original anti-seizing system

in these buildings is mainly made of uh

timber tyres you know placed

every one or one and a half meter most

of them

elements are uh partially degraded or

completely degraded in these buildings

but since as we see for we saw for

example in the tower of korea

it proved successful it is suggested

that first of all to

restore the original anti-seizing system

of course were possible because there

are also technical difficulties

and then to propose new strengthening

strategies

regarding the existing damage

pre-existing cracks were present

in all the case studies which

i discussed here but also others which i

did not

tackle in this in this presentation or

joints or

construction phases and this weakness

has proven to be you know one of the

main issues

with related to collapse or failure of

these

buildings so they have to be

let's say obsessed with with care you

know before

or when possibly not before the actual

earthquake

regards these structural analysis

application of this functionalities

method have proven useful

to understand the structural response

and prove with

scientific methods uh the causes of

failure which is in my opinion very very

important

because then not to leave you know space

to

you know debate but without some

scientific proof

and uh with regards to the adequate and

minimal strengthening the use of

structural analysis method

helps to guarantee the accurate but also

minimal

technical intervention which is a very

important

aspect in the restoration process

finally let me conclude here with an

acknowledgment

um that for cultural heritage

with our border and team leila nedi

stavri

anna anissa and yora who were part of

this amazing research so thank you for

your attention

thank you so much for that wonderful

presentation grigor and all

the attention to the technical detail as

well and the

analysis techniques um i saw a comment

as well in the chat about the diversity

of the presentations and indeed it's

something today that we really try to

focus on

we have presentations from anatolia

nepal albania india and peru

but we also wanted to ask you we will

have a follow-up summer

webinar on this topic of traditional

constructions and earthquakes

and so we wanted to ask you what regions

would you want to see represented in the

follow-up seminar

let us know in the chat even if you can

present on it send us an abstract we

will

send out the call for presentations

later

then now we will move from the balkan

back east

to india where arun menon will give us

the next presentation arun menon is an

associate professor of structural

engineering at iit madras

he also degree in architecture as well

as a phd in earthquake engineering from

the university of pavia italy

his research interests are in the

structural aspects of historical

constructions

the earthquake behavior of historical

masonry structures and the earth

and the development of earthquake

resistant structural masonry

he has been involved in conservation

projects in india bhutan myanmar and the

philippines

welcome arun

thank you thank you tim good day

good evening good afternoon to all those

who have joined into this

this fantastic ensemble of presentations

from different parts of the world

i thank the organizers of viscasa for

this opportunity

and i wish to take you through

some of the learning that

i've had with my co-workers

here in india and the neighboring

countries

so the title of my presentation this

evening is

seismic resistant traditional

construction features and structural

systems in the indian subcontinent

to begin with just to give you

an overview of seismic resistant

traditional constructions in india

it's important to sort of understand

the the extent of

seismicity the regions of seismicity

from the point of view of severity and

the point of view of

frequency of of occurrence of

earthquakes

and in that context it's important to

talk of the alpine himalayan

belt which has been a region of the

development of

a very large number of local seismic

cultures lsc's that we

refer to today this extends all the way

from

myanmar to the alps

um in in southern europe so you have

different forms of

earthquake resistant traditional

constructions uh that have developed

over time

well documented well understood

well researched in different parts of

the country and i think

the efforts to protecting them is an

area which requires

focus so as far as india is concerned

you have

the inter-plate events which is at the

boundary of

two of two tectonic plates and that's

the himalayan region and that's where

you have the

large earthquakes and they're not

they're rather frequent as well in this

region so

construction such as the dharjidwari

construction in kashmir

the construction in kashmir

the kathkuni construction himachal which

are all

locations sitting along the

plate boundary and therefore are

subjected to

interplayed type of large

frequent earthquakes but you also have

the

sm type of construction which is again

in the same region closer to

i mean in assam and regions around islam

like sikkim

called the accra construction so these

are part of the

local seismic cultures in these regions

but you also have constructions

which have shown to perform well during

earthquakes

and that's with specific reference to

what are called the poles

or constructions in gujarat

and this is a region which is very

different in seismicity from the rest of

the country because it's away from the

plate boundary and you have

interplayed intra plate earthquakes here

these are large earthquakes but not

so frequent in fact the 1819

butch earthquake in gujarat was followed

by the 2001

butch earthquake two large eight

magnitude eight earthquakes so

you have a difference in seismicity and

therefore

differences in the local seismic

cultures as well

it is therefore interesting to look at

we always try to

take lessons learn from regions where

there has been

significant earthquake activity let's

learn lessons from important earthquakes

large earthquakes every earthquake has

uh something to offer um in the broad

canvas of knowledge that develops over

time

uh it's interesting to look at regions

particularly in a country like india

where you have

regions of high seismicity and regions

of uh such low seismicity that

people have never heard of earthquakes

in certain zones so looking at and we

have this opportunity of studying some

of the stone constructions probate post

constructions in south india which is

the peninsula region of india where

earthquakes are

almost unheard of and we've never had

we've not had important earthquake in at

least 500 years

it's interesting to look at the um hypo

style halls

multi-pillar multi-pillared stone

constructions

and understand what's what gives them

safety against earthquake forces and

is there how well would they perform

in a surprise event in a in a maximum

considered earthquake for example for

the

for the region so we were at a point in

time

examining the earthquake safety of such

constructions as you see a four pillared

construction in a 16 pillar construction

and examining this considering that this

is a low seismic zone

looking at the co-defined levels of

earthquakes to even understand

how how would these perform uh compared

to the

prescribed levels in the seismic codes

and uh given that these are stone

constructions we're really looking at

monolithic elements beams and columns

and so limit analysis

is something that gives us a good

insight into the performance of these

rigid blocks

it's interesting to note that these

these constructions have

no interlocking between the monolithic

elements that is they're devoid of any

sort of positive connections

they do have a slight rough

edge and that is a marking of where they

should be seated with each other but

this is more more so for alignment

purposes during construction and not

to provide resistance to lateral actions

so you can assume that the positive

interconnections are

absent in these constructions and it's

it's actually interesting to note that

some of these constructions can actually

be vulnerable

to levels of earthquake shaking which

um south india has not experienced as i

said for at least 500 years from the

recorded history of

earthquakes so no positive connections

between these posts and lintels and

these appear

from limit analysis to be vulnerable to

overturning effects

of course there is a certain role

because of the frictional resistance

that it depends on

there is a role of pre-compression which

is which is extremely critical

and that's the sort of understanding we

would have but then

uh moving on to regions within india

where there is

significant earthquake activity it's

interesting to see the articulation of

joints and therefore one starts

understanding

the the necessity of those features

in the construction and the importance

of retaining them

in the construction in any

reconstruction or any rehabilitation

effort

the focus is particularly on

articulation of joints as i said the

absence of seismic resistant features

is what made us look at

the south indian constructions in

regions of low seismicity what is

expected to happen

however you should also understand that

the absence of seismic resistance

features in constructions

can be considered as an evidence of a

region's uh seismicity level and that is

a sort of a

confirmation of historical earthquake

catalogues if you

if you want but if you then look at

regions of

significant earthquake activity parts of

india and

particularly looking at nepal and you

see the

incorporation of specific features such

as tenant and motors joins

and sheer interlocking which is rather

significant these keys share keys that

are rather significant

in dimension gives you

an understanding of the role these play

the critical role that these play

in protecting the construction however

in this

particular case you do see collapse of

structures

despite having such features

and that is possibly due to two reasons

one that the

large amplitude of displacement

is is what is causing shearing of uh

damage to

stone shirkies or

in case of timber deterioration of the

timber would mean that it really does

not have

adequate interlocking in the event of of

an earthquake

um looking again at certain regions

where earthquake activity is significant

um

in in india looking at gujarat which

which i was mentioning

a while ago as regards the budge

earthquake

we do see evidence of use of uh devils

doubles in iron and devils in wood

this is a picture of an archaeological

monument a part of an archaeological

monument which

underwent partial collapse in the 2001

budge earthquake

but if one were to look at the

construction of the

um the walls of this minaret

you would see details of this nature

where two blocks of the stone masonry

adjacent blocks of the stone masonry

are provided with interconnection with

such

depressions into which stone and sorry

timber levels could be wood doubles

could be embedded

but they sit embedded in lime however

what happens over time

is that there is deterioration of the

lime because of action of

water moisture and once the lime

is uh is lost you have the bare

uh wooden devil that is exposed to the

elements and over time

the the wooden double completely

disappears and then you have just a pack

of stones

which are seated together without the

deformation capacity that this sort of

a detail was providing so

in the reconstruction efforts

particularly after an earthquake in

historical monuments of this nature and

the reconstruction efforts it's very

important to be able to identify the

role of such interventions

and replicate them or see if they're

being replaced with something

that it's conducive to the overall

characteristic of the construction

if we were to examine higher seismic

regions

like himachal pradesh which is again in

the himalayan range

kangra a region of a massive earthquake

in 1905

you can see constructions make use of

iron doubling of course this is again

uh from the point of view of providing

deformation capacity

but corrosion in metal unless it is

protected in

certain cases embedded in lead but not

in all cases

would then lead to damage in the stone

itself

moving on to the specific examples of

the traditional constructions in the

high seismic zones

the timber-laced masonry construction of

the thak in kashmir is one of the most

important and it's categorized as timber

laced masonry and you'll appreciate in a

moment why

it it is a timber-laced construction

system

if one way to examine the

architectural typology in the

construction

you would tend to think that this is a

sort of a multi-story isolation system

because the top constructions of kashmir

are really constructions that are about

uh

three stories and four stories um in

height

so the top constructions would actually

have a random rubble masonry

foundation over which you would have

a wooden blind band and this is a sort

of a runner that will go all around

sitting at the two at the two edges of

the

masonry wall the stone masonry random

rubble masonry plinth

and then the brick construction

commences

atop these these timber bands

now what is interesting is the

construction

makes use of a floor band

and the ceiling band and has the floor

joist

actually supported between these two

bands so as you can see

you have a floor band you have a seal

you have ceiling band and you have a

floor band and the timber joist which is

actually supporting the flow

is constructed on the joist but the

joist is embedded between

the um the ceiling band and the

floor band so you can see how the load

transfer is actually happening

directly to the timber system in the

floor

and the walls are interrupted

by these by the lacing in timber

so this this goes on for several floors

and then you have a roof system which is

again in timber

supported on the load bearing masonry

walls in a similar manner so you can

actually look at this as

a sort of a multi-story isolation system

but one has to remember that with the

timber

and the load-bearing masonry

construction deformation under gravity

of the timber occurs so sliding is not

something that is

permissible that doesn't really happen

but still you have a deformable

timber layer which is sandwiched between

masonry layers and

sort of the sub paneling that is

allowing for

reducing the brittle behavior of masonry

stories

so that's the uh the elevation of uh

construction an example from srinagar

called the fatehdel school

coming to the akra construction you can

actually see this sort of

the sort of lightweight timber framed

sub-panel construction system called the

acra acra

is akra really comes from

it's the name of the grass the ravenna

grass or the elephant grass which is

actually used to create

panels and these panels are at times

packed with

externally packed with mud or with lime

to pro to make it

durable and to also provide

environmental protection from the cold

weather

this is found in areas of sm high

seismic zone sikkim a high seismic zone

and so you have a lightweight

construction and you have sub paneling

with the timber

and you have a lightweight roof so you

have a very interesting system that is

highly resilient to earthquake action

problems with such constructions the

[Music]

foundation systems typically sitting on

hilly

slopes sitting on slopes you have the

random rubble foundation or the random

double plinth

and this is an area which often gets

damaged

and resetting of the entire construction

is possible because the superstructure

almost completely survives the

earthquake

the plinth needs to be reconstructed and

the superstructure can actually be reset

so you see examples here where

the damage is limited to the random

rubble plinth or the

random rubble foundation and the

structure sort of survives this is

another example of a school building

with this sort of a construction

uh lightweight sub panel timber framed

uh

excellent in its performance under the

earthquake but then you

as i said you might have because of the

damage to the foundation

movement of the structure and this

movement of the structure

you see the tilting of the building here

without even dismantling the entire

building

masons put the building back into a

vertical position

coming on to a region again uh which i

mentioned earlier gujarat

where uh the frequency of earthquakes is

frequency of big earthquakes is close to

180 to 200 years

and therefore there's always a question

whether the traditional constructions

there

really are designed or deemed to be

earthquake resistance because

of the observations of good performance

in the recent earthquakes

so we're looking at the poles of uh

of gujarat ahmedabad has a large number

of them and ahmedabad has been declared

as a world heritage city now

so you have as i said the difference

between the type of earthquakes in

the region of gujarat versus those of

the himalayan

area the in the intraplayed

earthquakes in gujarat versus the

interplayed earthquakes of

higher frequency in the himalayas

so this typology has

received certain um attention in the

recent years

on the good performance in the 2001

butch earthquake

and making particular reference to two

studies here one in 2006

and one much more recent in 2020 by

safika pancholi from sept university and

the intent was to understand

when you don't have a very formal system

following a local seismic culture local

seismic culture which is not very

evident in the construction

what is that is leading to good

earthquake performance

and in that context her study identified

that it is really the sheer wall

area the shear walls and the area of the

shear walls in the orthogonal directions

the orthogonal connections that are

introduced though not very

systematically

but they are present the regularity in

height again we're talking about

multi-story

constructions and the state of

conservation the state of conservation

plays a a very significant role

in today's context this being a world

heritage site with a number of these

structures

within the historic city the question is

these are residences and and how

is it that how are the um how is the

local population

able to retain these structures and um

despite an urge to make modifications or

convert them into newer facilities

this example here itself you could see

that there's a floor and reinforced con

reinforced concrete added above the

original structure it might have been a

replacement of a portion of the

structure with a new

the new construction so um here is a

category

which performs well under certain

conditions under earthquakes

because you don't see a formal

earthquake resisting system

systematically present in all the

examples that are remaining

but their good behavior in the

earthquake can actually be attributed to

a few geometrical and material related

features and therefore they need to be

addressed in any rehabilitation or

renovation effort so that this brings me

to

my concluding slide and and sort of

piecing together all that

i've been talking about while we are

talking of the earthquake

the earthquake effects on such buildings

and their resilience to earthquakes we

must also remember that

you're sitting in multi-hazard scenarios

in many cases the example that i'm

showing you here is of the wangdi for

throngs long in

bhutan which is of course affected by

earthquakes is also affected by

landslides because of the setting of the

structure

but was severely damaged and partially

collapsed because

of a fire so this sensitivity to

multiple hazards is important what may

be good for one may actually be

counterproductive for another hazard and

timber framing or timber elements in

masonry

is a challenge from this perspective but

one must

also appreciate the fact that it is not

heritage professionals or

people working on the preservation of

monuments who mostly live

in in these constructions and therefore

incorporation of new facilities

providing new services new aspirations

change lifestyles are aspects that we

really have to address of course if it

is a historical monument and a protected

monument it's a different matter

but when you're talking heritage

structures widespread

examples of heritage structures you

really must be

attentive to the fact that new uh

new directions in terms of the facility

with services is a reality and how how

does one address that

it is in this context that one needs to

identify critical parameters that

guarantee

inherent earthquake resistance as we saw

in the previous case of the pole

constructions

you also in certain cases might have to

incorporate earthquake resistant

measures

where being necessary timber for example

availability of timber is a problem in

many places today and there's also

legislation hilly areas that you cannot

use timber but one can

one has to really look at the fact that

timber is a renewable resource

and this is feasible so again looking at

the construction

reconstruction happening at vangdy for

throngsong and incorporation of certain

seismic improvement measures with

reinforced concrete

through stones is a fantastic example of

uh of trying to improve um

aspects of the structure which might

have a poor seismic performance

the same with the chassilin mandub in

bhaktapur which

collapsed in the 1934 earthquake was

reconstructed with certain

incorporated certain features

incorporated and survived the 2015

earthquake

i i leave it here thank you thank you so

much for that wonderful presentation

arun

from india we will move back west all

the way to peru

it is for our last presenter it's a

great pleasure to welcome claudia

cansino

claudia works at the getty conservation

institute as a senior project specialist

she graduated in architecture and urban

planning from the university of ricardo

palma in lima peru and early certificate

in conservation at ichrome in rome

she also holds a degree in business

administration from asan in lima and

received a master of science in historic

preservation with an advanced

certificate

in conservation from the university of

pennsylvania

currently she manages the urban

architecture initiative which includes

the

seismic retrofitting project the urban

architecture course in alain abu dhabi

and the terra 2022 congress in santa fe

new mexico

she also manages the retrofitting

component of

gci projects in

bagan that focuses on the conservation

there

welcome claudia

thank you team um good morning good

afternoon

and good night to everybody um

my presentation is going to try to

shortly describe

hopefully in 15 minutes how local

knowledge

over centuries has helped the design of

traditional retrofitting techniques for

urban buildings

in the peruvian andes i will use

at some points some of the research

testing

and implementation project develop as

part of the seismic

retrofitting project to explain the

efficacy of these

ancient techniques

earth construction is based on the use

of a very basic material

the soil which combined with the right

amount of water and compressed

air from the material base to produce

a variety of techniques that were

developed by humans

through time these techniques pictured

here from left to right

ram earth mad bricks or adobe in the

middle east and south america

cough water and dog among others

where the results of our ancestors

numerals tries and errors

making great use of their natural

resources

i don't know why it's not okay um

being the soil such an important element

for air construction i have placed here

a definition given by germany deltonico

in 1988 i would like us to concentrate

on the fact that the types the relative

proportion of these particles and the

forces between them

give the soil a particular character and

behavior

uben and your in 1994 disgrace schematic

structure and identify also three main

clay minerals that define the behavior

of a soil

these clay minerals are from the most

stable

to the most unstable one kylonian

allied and monorail light their

stability

in contact with water and air depends on

the strength between

internal air iconic or covalent bonds

which varies depending

of each type

these clay materials that are part of

the clay particles

interact with water at the molecular

level in many different ways

in molecular physics the van der waals

forces are distant dependent

interactions between atoms and molecules

these forces are present for example

between molecules of water

unlike ionic or covalent bonds between

for example

aluminium and silica layers seen in the

previous slides these forces are not a

result of

any chemical electronic bond and they

are comparatively

weaker and more susceptible to being

disturbed

the van der waals forces that attracts

water molecules among themselves are the

same forces that allow the different

clay materials to break

separate stay in dispersion and

reconnect

these forces therefore also allow to

create different

states of soil suitable for different

construction techniques

water despite being portrayed as the

enemy of earth construction it actually

contributed enormously to its creation

for me it is amazing that human beings

went from playing around

with these scientific principles to

create a series of techniques that

build impressive dwellings that are now

war heritage sites

and have survived over thousands of

years

there are for me also a testament of how

ingenious human beings are

the development of different urban

construction techniques around the world

are basically

based on the principles explained before

as you are recognized this is a map that

shows the seismic castles around the

world

and i have overlapped the regions

populated with urban sites

peru is located in a seismic area and

has

suffered earthquakes since the

prehispanic period

however this situation has also

supported the improvement of the local

building culture

to adapt to its environment and create

original retrofitting techniques

that are still in use in peru

peru has a variety of buildings made

with a series of present techniques that

has evolved through time

with the intention of the study of

standing against

seismic forces

there is evidence of potential seismic

isolation

at the archaeological site of canal

constructed around

3 100 before our era kerala is

considered one of the earliest urban

settlements in the americas and

was built in stone and earth recently

engineers from the pontificia

universidad catholica del penus has

researched a base simulation technique

found in this asian site which

apparently

stopped the out-of-plane collapse of

exteriors adobe walls

the use of the chikras a vegetable

fabric bag

with gravel stones inside apparently

dissipate the energy of seismic events

this is an earthly demonstration of how

ancient peruvians

made good use of available materials to

adapt to earthquake for centuries

you can find further results of the test

run and pucp

in several international publications

but in generally

it has been proved that the chakras

actually help to dissipate the seismic

energy

and preserve these ancient sites

archaeologists have also discovered some

early evidence of water and dog

panels in coral as seen in the images on

the left original slide

this technique that we call kincha in

peru

was apparently later used to build

residential dwellings

in northern peru as shown by the

political drawing

of the house of the lamborghini culture

on your right

i am not sure if the use of different

materials as part of an isolation

techniques

was also applicable for the construction

of the famous peruvian

andes which flourished during the inca

period from the 12th to the 15th century

of our era i guess further investigation

should be done particularly if you

consider that one of the most

significant sites in this seismic region

was from constructed with unreinforced

stone masonry

over a series of man-made antennas and

is still in place

several archaeologists have also noticed

the use of reinforcements

at the end of the wooden elements of

hypothetical groups at the williams at

machu picchu

this tradition of tying the ends of the

wooden beans to the masonry walls

was later used for the construction of

roofs during the spanish

visa royalty however

many centuries before the construction

of machu picchu the coast of peru was

full of a series of large earthen

complexes

built either in adobe like um the

guacaventille

ilima or ram earth or tapialas we call

it

like the site of kahamakia

the spanish arrived in 1532 and in 1536

uh there was a document called the real

prohibition that ordered the

construction of good houses for the

indian population of the viscerality of

peru

the regulation of madrid published in

1565

stipulated a restructuring world in

houses

had to be built in ram earth or dapial a

construction already used in the iberian

peninsula

harter red a well-known architectural

historian

has documented the construction of some

houses with tapial

in the 16th century in lima however the

majority of buildings and churches were

constructed in brink

and stone during that petrillius period

several documented earthquakes

as the one that you see here in the

paintings during the visa royalty period

shape

and modified these construction

techniques to make them more

specifically resistant

the first documented earthquake happened

in october

of 1606 and it apparently damaged

several buildings in lima

a second earthquake later in 1609

made the municipality of lima at the

time kabildo of lima

made it suggest to reduce the height of

the buildings

and to study traditional construction

techniques

already developed by the indians like

the kincha and the adobe

in 1681 there were several earthquakes

and particularly the one that happened

in october 20

which the archbishop of lima took right

to the king of

spain suggesting the construction of

only one

story buildings avoiding second history

houses in lima

the pisa roy conde de la moncloa end up

being

the person in church of the

reconstruction of the city of lima

after this earthquake and finally he

disposed

that if opera stories were needed to be

constructed

they should be built with kimchi

so as the drawing on your left shows

typically well in silima were built with

adobe in the first floor

and kincha in the second floor after the

1681

earthquake later the technique were

modified and i want to mention here that

this technique is very

is very similar to some techniques that

goron has shown you as in anatolia as

well as i don't have show us the

ecosystem in india so for me it's still

impressive that in different parts of

the world you can find similar

construction techniques

they will change over time as i said for

example at the panels in the second

floor

and had

adobe feelings in the lower part of the

panel

and we called this section sitaras and

they did

this probably to better connect uh

the panels with the wall below while the

third

floor in some cases had wooden diagonal

posts

at the corners to probably avoid

overturning

as part of the getty seismic

retrofitting project in peru

the pontificia universidad catolica

tested a replica of both type of king

child

for the first and second floor and an

additional historic panel demonstrating

their flexibility

their results were published and can be

downloaded as part of the provocation

that you can see

on the right

probably after the dome of the church of

santo domingo

in lima said that you can see here on

the right side of your slide

and was originally built by fred diego

matamoros in wood

cane and lime a few years before the

earthquake

survived the 1681 earthquake

it was probably because of these that

the recommendations that cuando de la

moncloa gave

the churches had to be built with

lighter domes and vaults

there is a theory that europeans borrow

the wooden construction techniques used

for ships

as you can see on the upper part of

the left images of the slide to design

lighter bones and domes so it is unclear

if the techniques used to build them to

build these bolts and

domes in a lighter way was brought from

the

iberian peninsula was designed in peru

or it was a combination of both

it seems it was after the dome of

september bingo was constructed and

survived an earthquake

that the famous uh groups of the francis

san francisco convent in lima were

constructed

nowadays all the visa royalty churches

of the course of peru are built with

this system

including the construction of wooden

also wooden columns and pillars like the

ones found in ika cathedral

as well as the cathedral of lima

in 1746 there was another earthquake

with its epicenter in lima around 3 000

and

around 3 000 churches and houses

collapsed

after the earthquakes the bise roy jose

manso de la mancha better known as

you can see here in this in the picture

ask a mathematician

luis godan to carry out a damage

assessment and provide technical

recommendations to improve the

structural behavior

of the existing structures so godan

in an official document suggested to the

copindo

the mandatory use of earthquake and

adobe instead of lime

brick and stone as construction

materials the use of kimchi

for wall partitions and the use of

kincha for

pinch award for the constructions of the

second and third studies of residential

buildings

[Music]

godan also suggested the increase of the

wheels

of adobe walls and finally the

construction of mattresses against

church

adobe walls the buttresses have proved

to be a very efficient retrofitting

solution

stopping particularly the overturning of

walls

and can be seen in most of the earthen

churches in the andes but also in some

of the rural churches of the coast

of peru

at some point the arch that normally

divides the nave

from the altar of these churches was

changed from

stone to kincha as well however i have

not been able to find exactly after

which earthquake this tradition was

changed

as you can see the tradition of building

with earth

have continued over centuries in peru

it's still very much in use and now not

only masons are training the job

but also the teaching of urban

construction and conservation is part of

the

curricula of architecture and

engineering schools

this has been of course an advantage for

the conservation of urban sites

there is a lot of experience

implementing conservation projects in

peru

taking into consideration the

seismically resistant

and or retrofitting techniques developed

through time

you can see in the video the

reconstruction of the kincha

arch for example at the church of

kunyutambo an srp implementation project

in cusco

as well as the installation of the

traditional wooden thai beans

nevertheless it will be important to

mention that the use of key thai

connections from outside

found in the inca developments in machu

picchu have always been used but the

quality

of the techniques have changed over time

a very detailed design of the kitai

connections

was developed as part of the

implementation project at kunyo tambo

the politician universia catholica also

ran a series of tests to understand the

performance of type beings on this type

of churches

the installation of wooden corner kits

to avoid

seismic damage at wall intersections

appear at some point during the

republican period

the use of these retrofitting techniques

within a conservation project

start formally probably during the 70s

and i was also surprised that this type

of corner keys

were also presented by a

grigor in previous presentations

for the church of kuno tambo a series of

wooden corner keys and collar beans

were designed modeled and implemented

based

on the construction expertise of our

peruvian colleagues

the study of the material in structural

characterization

as well as the modeling of these

techniques have been published as part

of the srp

and can be downloaded from the getting

website similarly the retrofitting

proposal for two historic earthen sites

in peru are presented there so you can

see more detail the development of the

conservation project

i have mentioned that the pontificial

diversity of catholica del peru has

worked with us as part of this project

but i would also like to mention that

the university of neo in portugal have

developed

the modeling and we have

work in close collaboration with the

ministry of culture in peru

it is very difficult to tell a linear

story

that explained the development of

seismically resistant construction

techniques in peru

i will say it has always been a

combination of local knowledge

professional expertise and trial and

errors after earthquakes

nowadays peruvian colleagues keep

working in

the further development of building

norms and codes to better preserve

these magnificent urban sites

so thank you so much for all your

attention and i hope you find

this uh presentation interested thank

you

thank you so much for that wonderful

presentation claudia

um as we've had our webinar for already

two hours i think we will

take a few of the questions that were

submitted unfortunately we will not have

time to answer all of them

i suggest we continue the discussion for

about another 20 minutes for the people

who can stay

so i am hoping that all the

panelists and presenters could turn on

their video

and then i will cycle through a set of

questions and this first one i would

like to throw to all panelists because i

think

it concerns a problem that all of us

deal with and it was raised by

pierre smarts from taiwan well

originally from belgium

just like me um so pierre says

related to kathmandu the temple but i

think we can relate it to other

places as well was not maintenance the

main problem

i imagine that there were quite a few

strong earthquakes before

ancient technology may not be perfect

but if it resisted a few earthquakes it

may not be that bad

i think pierre makes a very valid point

here that maintenance is important

and in a way we can think of buildings

in an analogy with with patients

seeing a doctor and so we could think of

an earthquake as a heart attack and so

the patients come

a patient comes to see his doctor and

says hey i've had five heart attacks

the first thing we don't say is ah okay

you've survived five you're fine

we wonder like will the next earthquake

kill him

will the next heart attack kill him so

what do you

what do you think about this um this

aspect of

of traditional construction haven't

proven itself

on the one hand but on the other hand

having these maintenance issues and this

constant traff threat due to earthquakes

who wants to

take a stab at that of our panelists

well i can

start if since it's

uh was uh

sort of uh in connection with uh the

customer

um our of course our uh

big question was that the custom under

didn't collapse during the 1934

earthquake and

sort of why didn't it collapse did we

really understand

uh the structure properly and i think

that really trying to understand the the

traditional

structures and technology is something

that we really need to work on

and i think it's also a question of

language

we had you know the artisans on the one

side and

sort of the experts and engineers on the

other side

and uh trying to

come to a a sort of a language that both

of them could

discuss in was not very easy

so i think it is uh you know sort of

still a lack of

sufficient understanding as on the one

side the other is we

saw that clearly that there was a lack

of

maintenance especially after

it became a monument which means before

there were people living in there people

using the monument

and in 1966 when the monument was sort

of restored and

uh looked at as a national monument

the people were kicked out and so you

can see that

you know sort of that lack of

sort of daily use of a monument uh it

was also probably

uh one of the reasons why uh you know

there was less maintenance

and monitoring sort of this daily

monitoring i think it all

comes together and now the the third

component

is we'd love to make it stronger and

better uh the question is what does that

mean

and there's uh you know we saw that

after the the the gurkha earthquake

that a lot of monuments that collapsed

were due

to a sort of inappropriate intervention

so

if we're going to introduce something

new into this old system

we better really understand its impact

and i think that is again

something that we really need to work on

we didn't do a good job in the past

and we really have to do more research

on that

thank you tim um i would like to add

uh to what i was saying that um

you know the the project at getty start

really

after the 2007 earthquake in peru and we

did a preliminary

study of the damage that some of these

historic sites suffer after this

earthquake

and i should say that the general

conclusion was

that really lack of maintenance was a

big

uh detriment on the you know

um poppy i mean

damage uh of the sites during the

earthquake either

interventions with new materials uh

without

you know any previous research uh

like cement um renderings over the bowls

and domes of these

uh kincha roofs at the churches

or you know the decay of the wooden

elements

uh that weren't working anymore um

so i think maintenance plays a really

big part

on the efficient efficacy of these

traditional retrofitting techniques

thank you both kai and claudia for those

insightful answers um i would like to

take this next question from

poonam mascarejas and she directs it to

um

kai and professor arun so we'll give it

to our goron arun and so

the question is can there is

reconstruction like in kathmandu be

informed of traditional sound practices

such as those from anatolia what would

be the cultural implications for

for the resident community can escarsa

promote

a built back better using traditional

systems

but not necessarily from the region

itself but from the international

repertoire within the material

typologies

you are muted gorin i didn't understand

the question

really so the question is whether we

should be

taking for example reinforcing

techniques that

have been tested and proven in anatolia

but might not be part of the traditional

repertoire

somewhere else like in peru or kathmandu

and whether

um iskarsa would promote

um a buildback better based on

techniques from another place that are

traditional

introducing them to um another area in

the world

i'm not sure if it is necessary because

each culture have its own

traditional methods maybe it's not

is searched very nicely

but but i'm sure

each country have their own

special traditional techniques

thank you um the next question is again

for

kai and it was from eugenie crete

she was saying if i understood well you

did

not follow the outcomes of the initial

structural assessment because of local

actors being attached to

rebuilt the same way wasn't it a very

good opportunity to understand deeper

the original seismic design

and not implement these quote

reinforcement strategies

there are a lot of examples of this kind

of reinforcement that turned out

counterproductive

so what is your opinion about the

initial structure assessment outcomes

compared to what was

actually done

and do you have more info to share about

the works that were done in

1966 1972 and 1984 so kai could you

comment a little bit more about

that initial assessment and then what

was done and what was not done

and why um

yeah uh of course the the

initial assessment was sort of a

standard procedure

which then was not accepted by

well uh quite a lot of uh people who

were

uh you know trying to get the monument

rebuilt uh

in a more traditional manner uh so again

it's a sort of

this dialogue between uh do we introduce

uh sort of so to say foreign materials

and

technology knowledge into these

traditional structures or not

i think that's an ongoing discussion but

in this case

uh there was uh really uh you know the

community

got together and said no we

want it rebuilt as it was now the

problem is

uh what does that mean as it was because

once it's collapsed we needed to sort of

look at you know the different elements

and

sort of reconstruct or redesign

the the the monument we had some

rough overall plans that were sort of

measured drawn

but not all the details so whatever uh

elements were found

uh you know it had to be sort of

reinterpreted based on

traditional knowledge and uh sort of

methods

and uh really the one of the only things

that

we you know well with the

reinterpretation

uh that was a process uh in itself but

then

uh the part that uh really uh was

uh discussed especially together with

the structural engineers was in

connection with the brick masonry

because this was one of the earliest

structures so it didn't even have the

the timber lacing which

later construction this timber lacing

was introduced all over

kathmandu now the point was you know

do we use this later introduced

technology which is local in the

structure

which uh which would have you know

not had it or for some reason it hadn't

been introduced

now uh yeah we there's a lot of

questions that arose we tried to

reinterpret it

in a manner that was sort of acceptable

to everyone

uh and and also of course working very

closely with the local artisans i mean i

think they were

very much involved in the decision

making process

so yes uh you know not everything is

is perfect uh you cannot you know there

are many questions that arose

uh and uh but i think uh you know uh

it sort of sets uh the the stage for

further research and yes i have much

more information

we're putting together a publication and

hopefully by

you know within the next few months uh

there'll be something uh

specific on this great thank you so much

kai uh we look forward to that

presentation uh

so tim i will i don't i hope you don't

mind but i would like to add

um like just to reinforce

what kai is saying regarding how

important is the interaction between the

academia

and the traditional craftsmen

and traditional knowledge you know after

the

1940 earthquake in peru there was a

strong

uh sort of push to stop earthen

construction in peru

they uh the the interventions on

historic buildings were

basically made in concrete but then it

was the academia the engineers

at that time from the pontificial

university in peru

and another university in louisiana

that actually got into this

and tried to develop some research

in collaboration with traditional uh

mason so it's it's always good to have

both uh you know both sectors

working uh together because you have the

local knowledge

but also you can support that local

knowledge with

scientific research thank you claudia i

think that's a very very valid

point um i'd like to give the next

question to um

grigor the question is from rafael di

cipoulo

and he's asking whether during the last

tower c restoration

if you considered insert um inserting

tension ties

and i also wanted to add immediately a

second question from arcadius

who asks

whether effective repair protection

solutions for the massive correct

structures

against earthquakes and aftershocks have

been considered so i think those two are

kind of linked

i was wondering if you comment could

comment um on that

please yes uh thanks for the question um

well i think that um you know in the

case of

of the towers you know there has been in

in some in

one part of the tower in the later

stages there has been the presence of

timber ties

now um the project will be finalized now

shortly

but we are considering inserting these

timber ties

in um in the structure

it is difficult but at least we would

like to insert at least the extremely

long

you know because we have like you know

in each level you have

usually three to four timber ties but at

least

the two external ones probably could be

could be

so we are um looking at this at this

possibility

and i think it's it's useless it is it's

useful sorry because

um you know it restores the original

type of factor now we do not have the

timber type because

we just see the voids because they are

degraded

well then with the regards to the

effective repair techniques

the solution on such a massive

structures

um you know i think that the application

of modern methods

you know gives us the possibility um

to see let's say the weakness of

the with of the original construction

technique you know

how it actually performed and make a

comparison with

what we saw on site and

try to make let's see the improvement

and actually test these

improvements virtually before we can

actually apply them inside

so i think i see that there is a

possibility here

using simulation models to actually have

effective repair solution for for this

there is an advantage for technology and

we should use it

that's my conclusion thank you grigor

and i think that's a great point and i

think also when

we saw claudia's presentation we saw

clearly how

you know traditional techniques were

studied first

and then extensive modeling and research

was done to actually virtually test if

they work and

i even believe that claudia in this

project the plan is also to monitor

even after implementation that the

techniques

work as expected and as models could you

comment a little bit on that please

uh yes uh i mean we're really happy

about this because

first of all we were the engineers from

the university of mino were able to go

back to the church

once the church was uh finished

and all was implemented and they

actually you know did some

sonic and dynamic testing to recreate

the model

once the techniques have been

implemented and it you know the results

were that the techniques were actually

working as originally

planned and then what we are going to be

doing

in the next uh couple of years

um you know after this pandemic is we're

gonna install some

uh monetary equipment that's gonna allow

us to

give us a better idea of how the

building performed

on the next five years i mean it's a

big investment for this church but i

think we can also use the equipment also

to

monitor other buildings that we plan to

implement

but the results i think of this uh

you know immediately after

implementation uh

modeling as well as you know the more

the structural monitoring over a period

of at least

five years is gonna be

published as well so yeah i think we're

very happy that we're gonna be able to

do that

thank you claudia um being mindful of

the time here that we're already going

20 minutes um over our scheduled

uh time frame i would like to invite

the panelists to make final comments if

they have any if they've seen a question

or have seen similarities that they

would like to address

um to finish up so any general

last remarks may i

uh of course tim arun here very quick

comment to just wrap up uh

that interesting discussion on whether

a technique for retrofitting adopted

adopted in in a certain region is

applicable in another

i think that that requires a certain

amount of application

because the laws of physics

do not change from place to place i

think once we

once we understand the materials

may differ the climatic conditions may

differ the construction

systems may differ but once we are able

to characterize that

laws of physics are the same everywhere

so i think there's a lot of inspiration

that we can draw from an understanding

and incorporation of a certain technique

in another place i think there's

abundance of knowledge that we can all

feed into

and learn from as examples thanks

thank you just a very short comment

uh i think we need much more research to

really understand these traditional

structures and

we should uh not jump to uh you know

introducing

uh a sort of other

uh technology

into these uh structures uh and uh just

looking at

the situation in kathmandu uh even

before the earthquake but uh also

with the work going on afterwards i

think there was really a lack of

research

uh the you know the reconstruction well

you know they jumped into it

with some changes interventions and it's

always the

built back better means you you know

introduce

new technology and i don't think

buildback better should mean

uh that i think we really need to work

on uh understanding the traditional

technology

and yes we might need to improve things

you know that's but then

with the detailed understanding of the

traditional structure and not just

you know putting in new things and i

think you know the the research is still

lacking we need to work on that thanks

i'd also like to add and i joined kai

in this respect and i always

advise to work with a history of

architects

because they study such

traditional techniques but they they

they don't know much about this

structure if you were

together then you can interpret what

they get

also with the archaeologists it's very

hard to work with archaeologists

because they don't like to share

but you can you can get

if you insist so much if you say that

your perspective is different

but working with different

disciplines is very important

thank you and with that call for a

multidisciplinary

study of more traditional construction i

think we can end this seminar

thank you all for all participants for

attending for asking

insightful questions and actively

participating in

the chat we look forward to seeing all

of you

in the follow-up webinar we will send

out a call for presentations

i saw a long list of interesting places

that we would want to hear from next

um so with that thank you thanks to all

of you

once more thank you to all the speakers

and hope to see you

um in our next webinar

thank you thank you very much thank

so you to you tim for the moderation